It is often necessary to transfer liquid from one location to another location. An example of such liquid transfer is the transfer of fuel. Before fuel can be made available to the consumer at a gas station, the fuel must be delivered to that location. The process typically begins with crude oil being pumped domestically or imported by ships or pipelines from other countries. Crude oil is then refined into the desired fuel, such as gasoline. The fuel is then stored in large storage containers or may be further distributed by additional pipelines, tankers, or barges to other locations. Eventually the fuel arrives at a bulk storage location. Tanker trucks are used to deliver the fuel from the bulk storage location to the gas station where it is made available to the consumer.
The fuel is stored in underground, or above ground storage containers. Most gas stations have various types of fuel available for purchase. Common examples include regular unleaded, premium unleaded, ethanol-gasoline mixes, and diesel. Each type of fuel is stored in a separate container.
Sometimes a fuel delivery is inadvertently put into the wrong tank. This can be a very costly mistake. For example, if a delivery of diesel fuel is unloaded into an unleaded fuel tank, the entire content of the tank must be pumped out and replaced. The mixed fuel that is removed must then be properly recycled or disposed of. The station will likely lose sales of that fuel until it can be replaced. If the mixed fuel is sold to consumers, the mistake may result in further damage and expense.